Workers Health & Safety Centre

Bladder cancer patients report work exposures to multiple carcinogens

New research into occupational histories of bladder cancer patients and the progression of their disease provides insight and incentive to prevent this difficult to treat cancer.
In this recent study published on October 21, 2020, University of Sheffield (UK) researchers collected and analyzed occupational histories from patients newly diagnosed with bladder cancer. From collected data researchers identified or confirmed specific hazardous substances, work sectors, occupations and work tasks, all associated with bladder cancer. The study also investigated the relationship of these exposures to the level of threat their cancers posed to their health.
Of the 454 patients, more than 40 per cent had bladder cancer categorized as high risk in terms of the cancer “stage” at diagnosis. In terms of cancer “grading”, almost 40 per cent were categorized as aggressive or high grade. High grade bladder cancer is likely to grow and spread rapidly and become life-threatening. Low grade cases are generally less aggressive, though still pose a 20 per cent chance of progressing to high grade.   
Following treatment, recurrence occurred in 56 per cent of the patients, one in four experienced progression of the disease, and more than one in three died within a median time of just over eight years following diagnosis. These findings and the experience of the many others who develop this disease suggest, bladder cancer is difficult to treat and cure. The researchers also point out earlier research has found one in 10 bladder cancer cases are work-related. Thus the case for bladder cancer prevention at work is a strong one.

Specific substances

The most common reported exposures included diesel fumes/fuels, coal/oil/gas by-products [combustion products including polycyclic aromatic hydrocarbons (PAHs)] and solvents. In most cases where specific exposures were reported, the patient reported exposure to multiple carcinogens linked with bladder cancer.  
High grade bladder cancer was found to be more common than low grade in workers exposed to crack detection dyes, chromium (a heavy metal), coal/oil/gas by-products, diesel fumes/fuel and aircraft fuel, along with solvents. Higher stage cancer was more frequent than expected in workers exposed to chromium, coal products and diesel exhaust fumes/fuels.

Sector profile

High grade bladder cancer was found to be more common than low grade in workers reporting employment in steel, foundry, metal, engineering and transport industries. In terms of cancer stage, higher than expected risk was found in those working in engineering and metal sectors.
Men with bladder cancer were found to work most commonly in engineering, steel and metalworking though a number also worked in the building sector. Women with bladder cancer were found to work most commonly in the service industries including hairdressing (hair dyes), laundry (solvents) and health care.

Job profile

The researchers also asked patients if they’d performed any of 33 tasks potentially linked with exposures thought to cause bladder cancer. The most common tasks included welding, making cement, use of lubricating/coolant oils, soldering/brazing, degreasing and work around forging or cooling operations.
Higher grade and stage of cancer was found to be associated with welding, the use of mineral oil lubricants and protective resins along with specific jobs with exposure to diesel fumes and fuels. More specifically, the data suggests electrical workers performing welding and soldering have a high risk of developing aggressive bladder cancer.
Additional evidence, beyond this study, suggest other exposures and industries are associated with bladder cancer, including aromatic amines such as 2-naphythylamine, benzidine, 4-aminobiphenyl and o-toluidine. These exposures are common in dyestuff manufacture along with rubber and other industries. Excess bladder cancer has also been observed in professional painters, machinists, textile workers and printers.

Ontario experience

Bladder cancer is the fourth most common malignancy in men and ninth most common in women in Ontario. All tolled, the Canadian Cancer Society estimates 4,450 Ontarians will be diagnosed with bladder cancer in 2020 with an estimated 445 as a result of workplace exposures.

A ground-breaking 2017 report by Cancer Care Ontario and the Occupational Cancer Research Centre (OCRC) offered more detail about the burden of bladder cancer here in Ontario, particularly associated with exposure to diesel engine exhaust (DEE) and PAHs. The report offered a set of recommendations for occupational cancer prevention, including the need to establish occupational exposure limits for whole diesel exhaust and/or diesel particulate and a mandatory training standard for WHMIS.

WHSC can help

The Workers Health & Safety Centre (WHSC) assists workplace prevention efforts with quality training and information services. In addition to GHS WHMIS training, we recently released a new Chemical Hazards program offered through our Joint Health and Safety Committee (JHSC) Certification Part II General Stream. Although, the program can also be delivered as a standalone course to all workplace parties. For workplaces looking to certify their joint health and safe committee, we offer JHSC Certification training – legally mandatory training critical to equipping workplace representatives in their work to protect workers from occupational carcinogens and other workplace hazards.  
All of these programs are offered through our virtual classroom allowing for the safety of participants and instructors during this COVID-19 crisis.
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Related resources:
Bladder cancer (OCRC)
WHSC WHMIS resources
WHSC Diesel exhaust fact sheet
Health and safety documentation tools
Research questions safe level of exposure to DEE